1. Field of the Invention
This invention relates to intake and/or exhaust valves for reciprocating internal-combustion engines, specifically:
(1) structures within a cylinder head that provide passages for delivering an air-fuel mixture to a combustion chamber and for removing combustion-product exhaust gasses: PA0 (2) a configuration of valves that control the flow of the air-fuel mixture into and the combustion products out of the combustion chamber; and PA0 (3) the mechanisms to operate the valves. PA0 (1) to overcome the inherent geometric limitations of poppet valves; PA0 (2) to reduce the pressure drop across engine intake and exhaust valves as compared to poppet valves; PA0 (3) to reduce the amount of unproductive work that an engine must perform by pumping intake mixtures and exhaust gasses; PA0 (4) to enhance even, symmetrical distribution of the intake fuel-air mixture to promote complete combustion; PA0 (5) to promote complete scavenging of combustion products from the engine cylinder; and PA0 (6) to increase engine efficiency and reduce the generation of pollutants by reducing pumping losses and ensuring complete, even combustion.
2. Prior Art
Reciprocating spark-ignition and compression-ignition internal combustion engines have generally used poppet valves for fuel and/or air intake and combustion product exhaust as appropriate. All four-stroke. spark-ignition engines currently in production use poppet valves. An engine's efficiency or power output can be increased if the area of its valves can be maximized. To increase valve area, many manufacturers are currently making multiple-valve engines, some very complex examples having as many as eight valves per cylinder.
Circular poppet valves have inherent geometric limitations. Poppet valves cannot use all of the available area of a cylinder head. No matter how many small, circular poppet valves are used, there will always be unused areas among the valves, the cylinder edges, and the spark plug or fuel injector. Engines with total valve area substantially smaller than available cylinder head area are inherently inefficient. The valve openings are constrictions to the flow of fuel-air mixtures and exhaust gasses. The engine must perform unproductive work to move these gasses across the constriction. These are commonly referred to as pumping losses. In addition, there is a pressure drop across the valve constrictions while the fuel-air mixture is flowing into the cylinder. This pressure drop limits the amount of fuel-air mixture that can enter the cylinder unless expensive, complex supercharging is used.
Finally, poppet valves are inherently asymmetrical to the cylinder axis. The fuel-air mixture is not uniformly distributed within the cylinder or around the spark plug that initiates combustion. Poppet valves can contribute to incomplete combustion with attendant loss of engine efficiency and increased unburned hydrocarbons in the exhaust stream.